textproduct: Albany

WHAT HAS CHANGED

Rainfall amounts have increased from the Capital Region/I-90 north and west tonight through tomorrow morning. The highest amounts are still expected closer to the I-84 corridor prior to 8 am tomorrow, where a Marginal Risk for Excessive Rainfall continues for the southeast Catskills, mid Hudson Valley, southern Taconics and NW CT. WPC QPF was used for tonight-tomorrow, as the NBM values were too low.

Min temps were lowered across the northern zones Mon night with radiative cooling environment with upper 30s to lower 40s for lows and pockets of mid 30s in the southern Adirondacks.

KEY MESSAGES

1) Showers and embedded thunderstorms will become widespread across most of the area tonight into Sunday morning. Localized downpours are expected especially for areas near and south of I-90.

2) A cold front will bring isolated to widely scattered thunderstorms mainly areas north and west of the Capital Region and southern VT Sunday afternoon and evening. A few storms could produce damaging winds and/or large hail.

3) It will be a mostly dry and cool start to next week with slightly below normal temperatures, with the next chance for showers arriving mid to late week.

DISCUSSION

KEY MESSAGE 1... High pressure continues to move east of New England this afternoon, as a warm front approaches from the lower Great Lakes Region and Ohio Valley. A short-wave trough lifts north/northeast towards the Piedmont/Mid Atlantic Region tonight. The isentropic lift increases ahead of the warm front for showers to break out and few t-storms ahead of the boundary tonight initially north and west of the Capital Region, and then expanding south and east across the region as a weak low tracks towards Long Island. Showalter index values lower to 0 to -2C on the NAM/EC and the latest mean MUCAPEs from the HREFS are generally <300 J/kg. Elevated instability is present. PWATs rise +1 to +3 STDEVS above normal into the 1.5-2.0" range with highest values values south and east of the Capital Region towards I-84. Some dynamical support from the right entrance region of an upper level jet streak over southeast Quebec/northern NY will help enhance the rainfall overnight coupled with efficient warm rainfall processes with high freezing levels or warm cloud depths. Some of the guidance continues to show some low/mid-level FGEN, but varies in the placement. The latest 3-km NAM looks like an outlier with a QPF bullseye of a few inches further north to the northern reaches of the Capital Region/Saratoga Region/srn VT. An uptick of QPF is supported by the CAMs and WPC and we have a half an inch to an inch from the Capital Region north and west with slightly lower amounts over the southern Dacks to account for any bands of heavy showers/t-storms.

The heavier rainfall amounts still look to be south and east of I-90 towards the mid Hudson Valley/NW CT and the southeast Catskills towards the I-84 corridor with 1-1.5" with locally higher amounts of 2" or so. The good news is that gridded FFG values in these areas are 1.8-2.5"/hr or 2.5-3.5"/3 hrs. The 6-hr FFG values are mainly 3-5"/6 hr in these areas. Latest HREFs indicates the heaviest rainfall for the southern most areas would be in the 12Z-18Z (8 am to 2 pm)/Sun time frame with probs >1" in 6 hrs 30-40% for portions of Dutchess, Berkshires and Litchfield Counties. 2" and 3" probs/6 hrs are lower. These same areas 12Z-15Z (8 to 11 am) Sun indicate rainfall probs >1" 70-90%; 50-70% up to the Capital Region/northern Taconics/southern VT and >3" rainfall in 3-hrs only 10-20% for portions of the mid Hudson Valley, southern Taconics and Litchfield Hills, NW CT. Ponding of water on roadways, poor drainage flooding of low-lying and urban areas looks like the greatest threats still. Rainfall rates may briefly peak at 0.5-1"/hr. The dry antecedent conditions will also help keep the flash flood threat low. Isolated flash flooding can not be ruled out in these areas (closer to I-84 and the mid Hudson valley/southern Taconics/NW CT south and east), where the Marginal Risk is in effect tonight into early tomorrow morning. A ERO Day 2 Slight Risk glances southern Litchfield Co in Day 2. The rainfall should diminish in the late morning. Lows fall back into the 50s to lower 60s

KEY MESSAGE 2...

Clouds will begin the day from most of the region. A lull in the rainfall is expected from the late morning into the early to mid pm. A prefrontal sfc trough and a cold front will be approaching from the west. Dewpoints will be in the 60s to around 70F in a few spots. The cold front is associated with a strong mid and upper level trough. Isolated- scattered showers and isolated- widely scattered thunderstorms will likely develop in the mid- late pm into the evening from northwest to southeast across the forecast area. CAMS continue to struggle in convective initiation and coverage. The best chance for some stronger storms to develop may be from the Capital Region and southern VT north and west associated with heights falls aloft and mean SBCAPEs on the HREFs are in the 750-1250 J/kg range with 0-6 km shear around 40-45 KT. The mid level lapse rates look marginal at 6-6.5C/km in these areas. The timing does not look great for a widespread severe threat, but an isolated threat with a few storms with damaging winds/marginal hail if enough heating and the better shear/CAPE overlap with the frontal forcing/upper level support. The better chance of showers and thunderstorms across the majority of the region looks like the late pm and night time period prior to midnight with the mid and upper level jet moving across southeast Canada. SPC continues the Marginal Risk for most of eastern NY and western New England (mainly north and west of the mid-Hudson valley, southern Taconics and NW CT). In the wake of the front. Strong cold advection occurs and it will become breezy and less humid. Lows in the 50s to around 60F with some mid/upper 40s in the southern Dacks.

KEY MESSAGE 3...

A cooler and drier air mass returns to open the week. Dewpoints fall in the 40s to lower 50s on Monday. It will become breezy with west/northwest winds 10-15 mph with some gusts 20-30 mph. Max temps will run below seasonal normals with mid 60s to lower 70s in the lower elevations and mid 50s to mid 60s over the hills and mtns. The winds subside Mon night with high pressure building in over NY and PA for near ideal radiational cooling conditions. Lows fall into the 40s with some mid/upper 30s over the southern Dacks, southern Greens and eastern Catskills. Some patchy frost may occur in the southern Dacks. We lowered mins below the NBM values closer to the GFSMOS numbers for this time frame. The fair and dry weather looks to last through the mid week until Thu when the next chance of showers and a few thunderstorms arrive with a cold front. Similar max temps for Tue as Mon, but then temps start to modify closer to seasonal to slightly above normal readings for Wed and Thu.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18z Sunday...VFR conditions prevail across all terminals this afternoon and will remain steady heading into this evening. However, clouds are already on the increase ahead of an incoming warm front that will track through the region overnight into tomorrow morning. Ceilings are expected to therefore develop later this evening around 25kft before gradually lowering throughout the evening into tonight. Periods of rain resulting from the incoming warm front will see visibility first drop into MVFR conditions while ceilings remain around 4-7kft to start. Once rain becomes steady and increases in rate, between 06-16z, MVFR to IFR ceilings will develop along with MVFR to IFR visibility. But, as this is a fairly progressive system, by the last couple of hours of the 18z cycle, rain should cease and conditions should be beginning to improve back towards VFR thresholds. Winds will remain breezy through this afternoon out of the southwest to southeast at sustained speeds around 5-10 kt. Throughout the overnight and into the end of the period, winds will become consistently southeasterly at speeds generally under 10 kt.

Outlook...

Sunday Night: High Operational Impact. Likely SHRA...TSRA. Monday: Low Operational Impact. Breezy. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: Low Operational Impact. Slight Chance of SHRA. Thursday: Moderate Operational Impact. Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.